I recently installed 6.1 and I am slowly getting up to speed with it. A few times when I have logged in as root, it says "You have new mail", but when I enter "mail", it says "No mail for root". By means of "cat /var/mail/root" I can see that there are indeed some messages spooled. Why isn't the mail program displaying them?

Are you really logging in as root? Or logging in as your usual user and using su?

Regardless, I usually forward all mail for root to myself. An easy way to do this is /etc/mail/aliases. In there, you will find a commented out alias for root. Change it to yourself, like this:

$ grep root /etc/mail/aliases
root: dan

Then all mail for root on this machine will go to dan's account.

You could also specify dan@example.org, instead of just dan.

Depending on what mail server you are using, you need to invoke the changes you made to that file: newaliases is what you'd use on a default system. If using postfix, then postalias /etc/mail/aliases is what you want.

As an experiment, I just added my normal account to the "wheel" group and that allowed me to log into root using su. Now mail displays the messages in the inbox. I guess there are some subtle differences between logging into root with su and sudo.